Vin Diesel and Paul Walker worked together on so many movies in the "Fast and Furious" franchise that sometimes it's hard to keep track. Over the course of the franchise's seven films, they co-starred in five of the movies, including "Fast and Furious 7" which is set for release in April of 2015. So, it's no wonder that when Walker tragically died in a car accident in 2013, Vin was understandably dealing with immense grief.

In a recent interview on "Live with Kelly and Michael," the actor admitted to co-host Michael Strahan that when Paul died he went through one of the darkest periods of his life. So much so, that he almost couldn't handle talking about the topic.

"And they're both looking at me right now like, is this going to be too much for him?" Vin said at first. "Because it could be. We could change the tone of the whole show real quick."

After gaining a bit of composure he admitted that it was one of the heaviest things he's dealt with.

"It's a heavy thing, Michael. You know?" Diesel said. "I grew up in the bouncer world, and we lost people while we were bouncing. But the brotherhood in Paul Walker was something completely different. It was someone that we... we grew up in the business together, and we became famous together, and we represented the biggest franchise together. He was my partner, and it’s a strange thing to... I've been acting all my life and they don't teach you in acting, how to mourn someone and simultaneously pretend they're in a scene with you."

Diesel is referring to how the movie continued filming "Fast and Furious 7" after Paul's passing, by using old footage, computer simulation, and even Walker's own brothers to fill in the bits and pieces.

"It's one of the darker moments in this, in my journey. Yeah. Yeah guys, you know it's a rough one. You all had people you love that passed away," Vin concluded.

But Vin is soldiering on despite his grief, and appears as Groot in "Guardians of the Galaxy," which opened this weekend. The oddball tree character has Diesel on stilts and saying the line "I am Groot" over and over again in different languages—surely this role offered good relief for Vin from more somber times.